The present invention relates to an unmanned transporting vehicle, and more particularly a guidance system for an unmanned transporting vehicle which automates the transportation of raw materials, products etc, in a factory, a storehouse or the like.
As guide means for an unmanned transporting truck, there are, for example, a method wherein an electric wire is buried in a floor, a magnetic field is generated by causing a high-frequency current to flow through the electric wire, and the unmanned transporting truck is run along the electric wire by detecting the magnetic field, and a method wherein a tape having a reflection factor unequal to that of a floor is stuck on the floor or such a line is depicted thereon, and the unmanned transporting truck is run along the tape or the line by detecting the difference of the reflection factors.
With the former method, the construction work of the floor is very laborious. Moreover, the floor construction work must be done each time the running route is altered, These incur the problems that the method lacks in adoptability for the alteration of the running route, and that it involves a high cost.
In contrast, with the latter method, it suffices to merely stick the tape or depiot the line on the floor. Therefore, the running route can be readily prepared or altered, at a low cost.
As the unmanned transporting truck which adopts the latter method, there has heretofore been known one wherein a large number of photoelectric detectors, each of which comprises in combination a light receiving element such as photodiode or phototransistor and a light emitting element such as fluorescent lamp or light emitting diode, are juxtaposed on the lower surface of the body of the transporting truck so as to cross the optical guide band such as tape or line (hereinbelow, simply written as `guide band`), and reflected light from the guide band is received to detect the lateral displacement of the transporting truck relative to the guide band, whereupon a steering mechanism is controlled so as to reduce the lateral displacement (refer to the U.S. Pat. No. 3,881,568 to Ando et al).
With the above unmanned transporting truck, however, the steering mechanism is controlled after the lateral displacement of the transporting truck relative to the guide band has arisen, resulting in the problem that the meandering amount of the transporting truck increases and makes it difficult to stop the truck in the vicinities of a machine tool etc.